Flexible and stretchable electronics are complete electronic circuits that have the ability to undergo reversible deformation while maintaining their intended functionality. The recent surge in flexible and stretchable electronics research and development has compelled researchers to come up with novel materials and processes that are well-suited for the advancement of this field.
Current state-of-the-art approaches to fabricating conductors that can survive elastic stretching involve an island-plus-serpentine approach, wherein rigid (non-stretching) electrical components are connected electrically using meandering (serpentine) solid metal interconnects. By employing this type of curved geometry to fabricate the device interconnects, localized strains are reduced, resulting in an overall device elasticity that exceeds that of the conducting metals in their bulk form. However, serpentine patterns require more real estate in the device layout, higher stretching can only be achieved where interconnects are not bonded to the substrate, and interconnects are prone to failure after repeated stretching cycles.
Eutectic blends of gallium-indium and gallium-indium-tin have also been investigated, because these room temperature liquid metal alloys are inherently stretchable, non-toxic, and have excellent conductivity. These have been used in strain gauges, stretchable capacitors, reconfigurable antennas, and self-healing circuits.
Direct-write and inkjet printing have been used to pattern gallium liquid metal alloys in different configurations and on various rigid and flexible substrates. However, high resolution features and non-planar substrate deposition have proved to be particularly challenging. Additionally, jetting techniques such as inkjet printing and aerosol jet printing, produce non-conducting gallium liquid metal alloy films that are made up of electrically-isolated, oxide-shell-stabilized, micro- and nano-particles.
What is needed, therefore, is at least one of an ink and a deposition system that reduces issues such as those described above, at least in part.